Well I have an inclosed room with a concrete floor that's 15ft long by 10ft wide. I am fed up with shaveings and to me haveing a dirt/sand filled floor would be better dust bathing and help keep bugs away, plus I think my girls would enjoy it a lot more than poopy shaveings. My question is, should I fill the first few inches with fill dirt then an inch or so of play sand? Or just all sand??? I think all sand would get too expensive if you ask me cuz I have a lot of square feet to cover. Or, could you guys make the best/cheapists solution for me? I'm not sure how much fill dirt is, all I know is my chickens desirve a better floor than what they have now.